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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e790d373a07e56cf3b873b4bacef1194b1dd7fff0d2dc1af4aa1506b846bc48' 
  AND token = 'Q5/xZMEvuAR2Me2kQRJwchOGMvwkFTnl4Ni1M2MtmlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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