SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749fcebdb6f4649e1400a7090a0c287196dd0ad51f74d96e037b1903b560fe45' 
  AND token = 'EkV7erPSBmvBCW187z2grnIe6BP5UuirSegfCaJE9yA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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