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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1878650004b7e9478c09a1a808564322ea810b9dca682c713f3eddb79f625b25' 
  AND token = 'Vehldy3p+TT2UNhx38g5sl6M4s6G2OTi7mccQmzTDyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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