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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a309f0fc2c52a8354c6163e7a9fd7aa5cbbeb5db6a6a2bb9ff6527241973c20' 
  AND token = 'ONgccEUb1XOxTNedi4vMTuUyqZHcmN36MOoyLsA7Kzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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