SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20fadd277f3d2cf2ac0406ab5d90c9c05bd5cbd1900edddd488f418d95c22566' 
  AND token = 'WSujPDIghiLIbIIJxSrVUvTyL3wS416xv8L5UcfPNSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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