SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02aa7bc878c2fcf123dd934a1496082d202663f46c184f313530460e2844fe1f' 
  AND token = '9juAfoCCDa2lAN8tZopa2rb5TJ4rpX4nfXFYim6BAoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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