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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc77dfe75f90f98e458f692f338795f2c7967a0b63c02e17ba280d87b7aedfc1' 
  AND token = 'nQxIfZ8Ww1W5QaUJNTPQ8Flbt5b6/KuYnL2Hkue1sEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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