SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c0da69c44c5281dfb8cbfe727b0a17875f5e4df9dd2f11044297fba36669758' 
  AND token = 'eXXjwr2YGZdf2GPGLnGS9sn8FGlAuH3TPm597/Lcbvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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