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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcdbd50b3d6b1b74bd0906afc0b7c276e34e7e10b7a61fd4d2e18701bdccd454' 
  AND token = '5tHdAL83hkFjaHenBZjQGlbn/u0pEQ83cz3z20Cz+mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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