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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6900507aa1f5543aa0c7f09951c0c001352a98cd8b1112e6aa391c9ee66e92a8' 
  AND token = 'dDuDQ3w6sJEDUgRj7JkEFYAJUWV7HdJxRr3LlL2JGKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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