SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45c672d26b653359a908e941b1e82f2f457bec08731c610f314d5749f31ef0cd' 
  AND token = 'zMbo2/tEpS1CSmaXT2v6H35bmIV1wohAMV45L0y+0tA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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