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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3899c2b9a0c002490a5f52be27126aad06f2a6f0c9613fd6db439016e19e0547' 
  AND token = 'ptLLsgPGKc6CoQ4IGFf7VdkibLv+5t6SIQr2UtS2Us0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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