SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '704627f130644d404c880b2befd3998502ddd6201ea75e741103e936a034d6c5' 
  AND token = 'Jt1Y1CXlAPjLsWKGW8CvPdj90SVP5g1HParexmw41xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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