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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1451bd835990cb1da21706090a09ed38e811a0e44b9594f8b228812a436728b4' 
  AND token = 'I40beF0rxp/ni+KdJaYWylkdYMf0nL/RUYLd1BBPomc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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