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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5bdb0860c03ce2251899aa3f527c0ed94505bbf683696ee63777e1b560b9db58' 
  AND token = '18yCTGNClHR0iW3mIGfe1jBn5DMnwC0GsFEXgqFLJxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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