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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df68ef43198e1b1f8eeae8056e637c1ac181699c35800ae37742fb57dca53cb5' 
  AND token = 'yZwEhcWwUOfGnPT4SE0glQ0FMMR0uJ4ZzAg0b/FBHxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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