SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efc600d0d0f0db3f78222110cf2e626d4b0baf963ae2051fd98cc341b9102422' 
  AND token = 'OiHutRjGL9X4E+ro1tJXGeb48k5jQXHJwQCa+Lk/krg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}