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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd70cefacba06e03080bac59e3998376f810fad5694424a9dd4eec0252ada2bb7' 
  AND token = 'hM+KM1//HNx2uVHiL2aAByaAXLAC8IpsTdJchKWMoFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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