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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18d6d562bba9dc7b115749489506113fda540e899e75868529331388d3a4301a' 
  AND token = '77vFwOqODeFaNofj2xnfR+pFj0DpGD8MorpaPI8L5eM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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