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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c1710644870290adfd4d35688c44bfe01c310ef8ffbce14cc9cd2aadfe727da' 
  AND token = 'L3Wk3zP5ER6+KyuqkLcRtlvTtoj/L1LwE080h8/DdKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}