SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2cba340fca4f9dd2fad2898e4c6254805a0e89f73bf5bd9784bdd4808bcfd49a' 
  AND token = 'U+To2ckt2HR7UfRIbBrvne7SjRP1rjkv0pnBQAbJdvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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