SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f12a045c3b0909156024cd77f89275b61be3b827dec6b1bef4ad834fbb1048a4' 
  AND token = 'c1TkNLAimVEz6mZQshvEfL7aTZYUU8zlLV2LZjOZvHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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